Turkey Tail

Polysaccharide-K (PSK), is a protein-bound polysaccharide isolated from Trametes versicolor, which is used as an immune system boosting agent in the treatment of cancer in some European countries as well as China and Japan. In Japan, PSK is approved as an adjuvant for cancer therapy[1] and is covered by government health insurance. Otherwise, there is no regulatory approval of this agent for any clinical use in other developed countries.

PSK displays anticancer activity from preliminary laboratory assessments in vitro,[3] in vivo[4] and in human clinical trials.[5] Preliminary research has shown that the PSK might reduce mutagen-induced, radiation-induced, and spontaneously-induced development of experimental cancer cell preparations.[6] PSK has shown to be beneficial as an adjuvant in the treatment of gastric, esophageal, colorectal, breast and lung cancers.[7] Preliminary human clinical trials indicate PSK might reduce cancer recurrence when used as an adjuvant[5][8] and other basic research has demonstrated the mushroom can inhibit certain human cancer cell lines in vitro.[9][10][11] Further in vitro studies have shown that a nutraceutical blend (MC-S) of PSK, lentinan and other fungal extracts might also inhibit cancer cell proliferation under laboratory conditions.[12]

The MD Anderson has reported that it is a "promising candidate for chemoprevention due to the multiple effects on the malignant process, limited side effects and safety of daily oral doses for extended periods of time."[13] At present, however, there are no approved drugs or scientifically verified anti-disease activities resulting from this mushroom.